Printed circuit board and manufacturing method therefor

ABSTRACT

A printed circuit board of a card edge connector type includes interconnections formed on a surface of a substrate to be electrically coupled to respective connecting terminals formed by electrolytic plating on an edge of the substrate, and connecting terminal-forming wirings being respectively in connection with the interconnections, when the connecting terminals are formed by the electrolytic plating. The interconnections are electrically isolated from the connecting terminal-forming wirings by process openings formed in the substrate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to a printed circuit board of a cardedge connector type and a manufacturing method therefor.

2. Description of the Related Art

A card edge connector type of printed circuit board is known, asdisclosed, for example, in Japanese Patent application Publication No.2005-26020. This printed circuit board of the card edge connector typeincludes multiple connecting terminals formed on one end of the printedcircuit board, and is inserted into or pulled out of a correspondingconnector. The above-described card edge connector type of printedcircuit board is configured in such a manner that distances from a cardedge to the connecting terminals are selectively varied in order toadjust touch timings between the respective connecting terminals andcorresponding contacts on the connector, when a card edge portion isinserted into the connector.

In a case where the above-described connecting terminals that can adjustthe touch timings with the connector are formed by electrolytic goldplating, connecting terminal-forming wirings are needed for forming theconnecting terminals. However, when the connecting terminal-formingwirings are arranged between the card edge and the connecting terminals,there is the possibility that the function of adjusting the touchtimings cannot be assured. Accordingly, the connecting terminal-formingwirings have to be coupled respectively to the connecting terminalsthrough signal lines connected to the connecting terminals.

Meanwhile, if the circuit is operated with the connectingterminal-forming wirings respectively coupled to the signal lines, thiscauses impedance mismatching or signal transmission loss. In particular,in a case where the connecting terminal-forming wirings are connected tothe signal lines that transmits high-speed signals of as high as GHzband.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above circumstancesand provides a printed circuit board and a manufacturing methodtherefor, in which it is possible to eliminate the influence on thecircuit characteristics of connecting terminal-forming wiringsrespectively connected to signal lines or the like so as to formconnecting terminals by electrolytic plating on a printed circuit boardof a card edge connector type.

According to one aspect of the present invention, there is provided aprinted circuit board of a card edge connector type including:interconnections formed on a surface of a substrate to be electricallycoupled to respective connecting terminals formed by electrolyticplating on an edge of the substrate; and connecting terminal-formingwirings being respectively in connection with the interconnections, whenthe connecting terminals are formed by the electrolytic plating. Theinterconnections are electrically isolated from the connectingterminal-forming wirings by process openings formed in the substrate.With the above-described configuration, the process openings are formedafter the interconnections and the connecting-terminal forming wiringsare respectively coupled. Thus, the interconnections and theconnecting-terminal forming wirings can be isolated electrically,thereby eliminating the influence on the circuit characteristics of theconnecting terminal-forming wirings with ease.

According to another aspect of the present invention, there is provideda printed circuit board of a card edge connector type including: twointerconnections formed in parallel on a surface of a substrate to beelectrically coupled to respective connecting terminals formed byelectrolytic plating on an edge of the substrate; and a connectingterminal-forming wiring being commonly in connection with the twointerconnections, when the connecting terminals are formed by theelectrolytic plating. The two interconnections are electrically isolatedfrom the connecting terminal-forming wiring by a process opening formedin the substrate, the process opening being commonly connected to thetwo interconnections. With the above-described configuration, theconnecting terminal-forming wiring can be commonly provided to the twointerconnections.

According to still another aspect of the present invention, there isprovided a manufacturing method of a printed circuit board of a cardedge connector type including: forming interconnections and connectingterminal-forming wirings by electrolytic plating before connectingterminals are formed by electrolytic plating on an edge of a substrate,so that the interconnections are respectively connected to connectingterminals and the connecting terminal-forming wirings are respectivelyconnected to the interconnections; and forming process openings in thesubstrate to electrically isolate the interconnections from theconnecting terminal-forming wirings.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention will be described indetail with reference to the following drawings, wherein:

FIG. 1A is a top view illustrating a configuration of a printer circuitboard in accordance with an exemplary embodiment of the presentinvention;

FIG. 1B is a cross-sectional view taken along a line A-A shown in FIG.1A;

FIG. 2 is a cross-sectional view showing a state before process openingsare formed on the printed circuit board;

FIG. 3A is a top view illustrating a configuration of the printedcircuit board in accordance with another exemplary embodiment of thepresent invention;

FIG. 3B is a cross-sectional view taken along a line A-A shown in FIG.3A;

FIG. 4A is a top view showing a state before process openings are formedon the printed circuit board;

FIG. 4B is a cross-sectional view taken along a line A-A shown in FIG.4A;

FIG. 5A is a top view illustrating a configuration of the printedcircuit board in accordance with yet another exemplary embodiment of thepresent invention;

FIG. 5B is a cross-sectional view taken along a line C-C shown in FIG.5A;

FIG. 6 is a top view showing a state before process openings are formedon the printed circuit board;

FIG. 7 is a variation example of the configuration of the printedcircuit board shown in FIG. 5A and FIG. 5B;

FIG. 8A is a top view illustrating a configuration of the printedcircuit board in accordance with yet another exemplary embodiment of thepresent invention;

FIG. 8B is a cross-sectional view taken along a line D-D shown in FIG.8A;

FIG. 9A is a top view showing a state before process openings are formedon the printed circuit board;

FIG. 9B is a cross-sectional view taken along a line D-D shown in FIG.9A;

FIG. 10A and FIG. 10B show yet another exemplary embodiment inaccordance with the present invention; and

FIG. 11A and FIG. 11B show yet another exemplary embodiment inaccordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A description will now be given, with reference to the accompanyingdrawings, of embodiments of the present invention.

FIG. 1A, FIG. 1B, and FIG. 2 illustrate an exemplary embodiment of thepresent invention. FIG. 1A is a top view illustrating a configuration ofa printed circuit board. FIG. 1B is a cross-sectional view taken along aline A-A shown in FIG. 1A. FIG. 2 is a cross-sectional view showing astate before process openings are formed on the printed circuit board.Referring to FIG. 1A and FIG. 1B, the printed circuit board is of a cardedge connector type having multiple connecting terminals 50, 60, and 70are formed on a surface of one edge of a multilayer substrate 10(hereinafter, simply referred to as substrate 10), by electrolytic goldplating. The substrate 10 is made of a dielectric material such as anepoxy resin or the like. The printed circuit board is inserted into orpulled out of a connector, not shown, in directions of two-headed arrowsshown in FIG. 1A. At this time, the connecting terminals 50, 60, and 70and the edge of the substrate 10 are provided in such a manner that thedistance between the connecting terminals 50 and the edge is almostidentical to that between the connecting terminal 60 and the edge, andthe distance between the connecting terminal 70 and the edge isselectively longer than those between the terminal 50 or 60 and theedge.

Also, interconnections 20, 30, and 40 electrically coupled to theconnecting terminals 50, 60, and 70 are formed of a conductive materialsuch as copper or the like on a surface of the substrate 10 by a knowntechnique. The interconnections 20, and 30 are lines provided forhigh-speed signals that transmit, for example, high-speed signals of ashigh as GHz band. The interconnection 40 is provided for a power supply,ground, or low-speed signals. Via hole platings 80 made of copper or thelike are respectively formed to serve as via hole conductors and extendto given depths of the interconnections 20, 30, and 40, and arerespectively connected to the interconnections 20, 30, and 40.

Connecting terminal-forming wirings 100 are provided as an inner layerof the substrate 10, as shown in FIG. 1B. The connectingterminal-forming wirings 100 are used with being connected to theinterconnections 20, 30, and 40 respectively, while the connectingterminals 50, 60, and 70 are being formed by the electrolytic goldplating. The connecting terminal-forming wirings 100 are patterned, forexample, by a conductive material such as copper or the like, and arerespectively formed to correspond to the connecting terminals 50, 60,and 70. Process openings Mh are formed in positions that correspond tothose for forming the via hole platings 80 so as to extend to givendepths in the substrate 10 (in other words, so as not to pierce throughthe substrate 10) and electrically isolate the correspondinginterconnections 20, 30, and 40 from the connecting terminal-formingwirings 100.

On the printer circuit board before the process openings Mh are formed,the via hole plating 80 is electrically coupled with the connectingterminal-forming wiring 100, as shown in FIG. 2. The printer circuitboard of FIG. 2 is formed by a known technique. The connectingterminal-forming wirings 100, the interconnections 20, 30, and 40, andthe via hole platings 80 are formed, and the connecting terminals 50,60, and 70 are then formed by the electrolytic gold plating with the useof the connecting terminal-forming wirings 100. Here, the connectingterminal-forming wirings 100, the interconnections 20, 30, and 40, andthe via hole platings 80 are electrically coupled to respectivelyestablish electrical connection paths so as to provide the connectingterminals 50, 60, and 70.

Then, the connecting terminals 50, 60, and 70 are formed by a knowntechnique of the electrolytic gold plating. Subsequently, the processopening Mh is processed to a given depth of the substrate 10 in theposition that corresponds to the position where the via hole plating 80is formed, from the backside of the substrate 10 by use of a processmachine equipped with a drill, so the via hole plating 80 and theconnecting terminal-forming wiring 100 are disconnected. As describedheretofore, as shown in FIG. 1A and FIG. 1B, the connectingterminal-forming wirings 100 are electrically isolated from theinterconnections 20, 30, and 40, thereby making it possible to preventthe impedance mismatching and signal transmission loss caused byunnecessary connections between the connecting terminal-forming wirings100 and the interconnections 20, 30, and 40.

FIG. 3A through FIG. 4B show another exemplary embodiment in accordancewith the present invention. FIG. 3A is a top view illustrating aconfiguration of the printed circuit board in accordance with anotherexemplary embodiment of the present invention. FIG. 3B is across-sectional view taken along a line A-A shown in FIG. 3A. FIG. 4A isa top view showing a state before process openings are formed on theprinted circuit board. FIG. 4B is a cross-sectional view taken along aline A-A shown in FIG. 4A. Hereinafter, in FIG. 3A through FIG. 4B, thesame components and configurations as those of the above-describedexemplary embodiment have the same reference numerals.

The points of difference between the present embodiment and theabove-described embodiment are now described. The via hole platings 80are formed adjacently to the interconnections 20, 30, and 40, as shownin FIG. 4A and FIG. 4B, and then the connecting terminal-forming wirings100 are respectively connected to the corresponding interconnections 20,30, and 40, in accordance with the present embodiment. Subsequently, theprocess openings Mh that piece through the substrate 10 are formed inthe positions that correspond to those for forming the via hole platings80, so the connecting terminal-forming wirings 100 are electricallyisolated from the interconnections 20, 30, and 40. Here, the positionsand sizes for forming the via hole platings 80 and those of the processopenings Mh are determined in consideration of the interconnections 20,30, and 40, so that the interconnections 20, 30, and 40 have designedwidths. According to the configuration employed in the presentembodiment, the process openings Mh pierce through the substrate 10,thereby facilitating the process.

FIG. 5A, FIG. 5B, and FIG. 6 show yet another exemplary embodiment inaccordance with the present invention. FIG. 5A is a top viewillustrating a configuration of the printed circuit board in accordancewith yet another exemplary embodiment of the present invention. FIG. 5Bis a cross-sectional view taken along a line C-C shown in FIG. 5A. FIG.6 is a top view showing a state before process openings are formed onthe printed circuit board. Hereinafter, in FIG. 5A through FIG. 6, thesame components and configurations as those of the above-describedexemplary embodiments have the same reference numerals.

In the present embodiment, the via hole plating 80 is not provided onthe interconnection 40. Instead, as shown in FIG. 6, theinterconnections 20, 30, and 40 are formed on the surface of thesubstrate 10, and a connecting terminal-forming wiring 100A is providedto be connected to the interconnection 40 on the surface of thesubstrate 10. In addition, as shown in FIG. 5A and FIG. 5B, the processopenings Mh that extends through the substrate 10 are formed for theinterconnections 20 and 30 in the positions that correspond to those forforming the via hole platings 80. The process opening Mh that extendsthrough the substrate 10 is formed for the interconnection 40 in theposition that corresponds to that for forming the via hole plating 80 tocut across the connecting terminal-forming wiring 100A. The positionsand sizes of the process openings Mh are determined in consideration ofthe interconnections 20, 30, and 40, so that the interconnections 20,30, and 40 may have designed widths. As stated, it is possible form theconnecting terminal-forming wiring 100A at the same time in the processof forming the interconnections 20, 30, and 40, by arranging theconnecting terminal-forming wiring 100A on the surface of the substrate10. Also, the connecting terminal-forming wiring may be formed for theinterconnection 20 or 30 on the surface of the substrate 10. In FIG. 6,the process opening Mh for the interconnection 40 is a through hole.However, referring now to FIG. 7, for example, the process opening Mhmay be a blind hole that extends to a given depth in the substrate 10.This enables a lower layer of the process opening Mh to be utilizedefficiently.

FIG. 8A through FIG. 9B show yet another exemplary embodiment inaccordance with the present invention. FIG. 8A is a top viewillustrating a configuration of the printed circuit board in accordancewith another exemplary embodiment of the present invention. FIG. 8B is across-sectional view taken along a line D-D shown in FIG. 8A. FIG. 9A isa top view showing a state before process openings are formed on theprinted circuit board. FIG. 9B is a cross-sectional view taken along aline D-D shown in FIG. 9A. Hereinafter, in FIG. 8A through FIG. 9B, thesame components and configurations as those of the above-describedexemplary embodiments have the same reference numerals.

On the surface of the substrate 10 employed in the present embodiment,referring to FIG. 9A and FIG. 9B, two interconnections 20 and 30 arearranged in parallel and the process opening Mh that pierces through thesubstrate 10 is arranged between the two interconnections 20 and 30.Referring to FIG. 8B, a connecting terminal-forming wiring 100 isprovided as an inner layer of the substrate 10. The connectingterminal-forming wiring 100 is commonly provided to the twointerconnections 20 and 30.

As shown in FIG. 9A and FIG. 9B, before the process opening Mh is formedon the printed circuit board, the connecting terminal-forming wiring 100is formed as an inner layer of the substrate 10, the interconnections 20and 30 are formed on the surface of the substrate 10, an interconnection200 is formed on the surface of the substrate 10 to connect theinterconnections 20 and 30, and the via hole plating 80 is formedbetween the interconnections 20 and 30 to connect the interconnection200 and the connecting terminal-forming wiring 100. Subsequently, thevia hole plating is formed in the position that corresponds to that forforming the via hole plating 80. The via hole plating 80 and theinterconnection 200 are wholly or partially removed to electricallyisolate the two interconnections 20 and 30 from the connectingterminal-forming wiring 100. Here, the position and size for forming thevia hole plating 80 and those of the process openings Mh are determinedin consideration of the interconnections 20 and 30, so that theinterconnections 20 and 30 have designed widths.

It is thus possible to reduce the number of processed necessary for theprocess of the process opening Mh, by forming the via hole plating 80and the connecting terminal-forming wiring 100 commonly provided for theinterconnections 20 and 30 that transmit high-speed signals.

FIG. 10A and FIG. 10B show yet another exemplary embodiment inaccordance with the present invention. Hereinafter, in FIG. 10A throughFIG. 10B, the same components and configurations as those of theabove-described exemplary embodiments have the same reference numerals.In this printed circuit board, the process opening Mh that piercesthrough the substrate is isolated from conductive layers composed of awiring layer for ground 300, a wiring layer for power supply 310, and awiring layer for signal 320. In other words, in accordance with thepresent embodiment, the conductive layers composed of the wiring layerfor ground 300, the wiring layer for power supply 310, and the wiringlayer for signal 320 are formed in the forming process so as to saveregions where the process opening Mh pierces through. With theafore-described configuration, when the process opening Mh is processedwith a drill, no drilled residue particles are generated from therespective conductive layers, thereby preventing the respectiveconductive layers being short-circuited. Referring now to FIG. 11A andFIG. 11B, for example, it may be configured such that only the wiringlayer for ground 300 is in contact with the process opening Mh (whichpierces through the substrate 10). There is no possibility ofshort-circuiting, if only one layer is in contact with the processopening Mh.

In the above-described embodiments, a description has been given of acase where a conductive via hole is formed by plating. However, thepresent invention is not limited to this case. The via hole may beformed by another method. In the above-described embodiments, theconnecting terminals are formed by electrolytic gold plating. However,another type of electrolytic plating may be employed for forming theconnecting terminals.

In the above-described embodiments, a description has been given of acase where the process openings are processed to electrically isolateall the interconnections 20, 30, and 40 from the connectingterminal-forming wirings 100. However, it may be configured such thatthe process openings are processed only for the interconnections 20 and30 that transmit high-speed signals so as to electrically isolate fromthe connecting terminal-forming wiring.

According to one aspect of the present invention, there is provided aprinted circuit board of a card edge connector type including:interconnections formed on a surface of a substrate to be electricallycoupled to respective connecting terminals formed by electrolyticplating on an edge of the substrate; and connecting terminal-formingwirings being respectively in connection with the interconnections, whenthe connecting terminals are formed by the electrolytic plating. Theinterconnections are electrically isolated from the connectingterminal-forming wirings by process openings formed in the substrate.

In the above-described printed circuit board, the connectingterminal-forming wirings may be formed as inner layers of the substrate,and may be isolated from the interconnections by the process openingsthat extend to a given depth in the substrate. The above-describedconfiguration eliminates the necessity of providing a through hole inthe substrate, thereby making it possible to prevent the process openingformed in the substrate from affecting the conductive layers formed asinner layers in the substrate.

In the above-described printed circuit board, the connectingterminal-forming wirings may be formed apart from a card edge connectorportion on the surface of the substrate, and may be electricallyisolated from the interconnections by the process openings that piercethrough the substrate. With the above-described configuration, it ispossible to form the interconnections and the connectingterminal-forming wirings at the same time, thereby facilitating theformation of the connecting terminal-forming wirings.

In the above-described printed circuit board, the interconnections mayinclude interconnections that transmit high-speed signals; and theprocess openings electrically isolate at least the interconnections thattransmit the high-speed signals from the connecting terminal-formingwirings. With the above-described configuration, it is only necessary toform the process openings to isolate the connecting terminal-formingwirings from the signal lines that transmit high-speed signals thataffect the circuit characteristics.

In the above-described printed circuit board, the process openings maybe isolated from a conductive layer formed as an inner layer of thesubstrate. With the above-described configuration, it is possible toprevent the problem such as short-circuiting caused by the drilledresidue particles.

In the above-described printed circuit board, the process openings maybe in contact with only one layer out of multiple conductive layersformed as inner layers. With the above-described configuration, it ispossible to process a layer having a large area such as a ground layerand to prevent the problem such as the short-circuiting caused by thedrilled residue particles, when only one layer is in contact with theprocess opening.

In the above-described printed circuit board, via holes may be formed torespectively connect the interconnections and the connectingterminal-forming wirings. With the above-described configuration, it ispossible to connect the interconnections formed on the surface of thesubstrate and the connecting terminal-forming wirings formed as innerlayers by the via holes, and the processing can be facilitated byforming the process openings in the position that correspond to thosefor forming the via holes.

In the above-described printed circuit board, the electrolytic platingmay include electrolytic gold plating. With the above-describedconfiguration, it is possible to form the connecting terminals with theuse of highly conductive gold plating and to retain the thickness of theconnecting terminals sufficiently as compared to those with the use ofnonelectrolytic plating.

According to an exemplary embodiment of the present invention, it ispossible to eliminate the influence on the circuit characteristics ofthe connecting terminal-forming wiring connected to the signal line orthe like so as to form the connecting terminals on the printer circuitboard of the card edge connector type by electrolytic plating.

The present invention is not limited to the above-mentioned embodiments,and other embodiments, variations and modifications may be made withoutdeparting from the scope of the present invention.

The present invention is based on Japanese Patent Application No.2005-212427 filed on Jul. 22, 2005, the entire disclosure of which ishereby incorporated by reference.

1. A manufacturing method of a printed circuit board of a card edgeconnector type comprising: forming interconnections and connectingterminal-forming wirings by electrolytic plating, before connectingterminals are formed by electrolytic plating on an edge of a substrate,so that the interconnections are respectively connected to connectingterminals which are formed on a surface of the substrate, and theconnecting terminal-forming wirings are respectively connected to theinterconnections and are formed as an inner layer of the substrate; andforming process openings in the substrate to electrically isolate theinterconnections from the connecting terminal-forming wirings, theprocess openings being isolated from a conductive layer formed asanother inner layer of the substrate.
 2. The manufacturing method asclaimed in claim 1, wherein the forming the interconnections and theconnecting terminal-forming wirings includes: forming the connectingterminal-forming wirings as inner layers of the substrate; forming theinterconnections on a surface of the substrate; and forming via holeconductors that electrically connect the interconnections and theconnecting terminal-forming wirings, respectively; and wherein theforming the process openings includes forming the process openings inpositions that correspond to those for forming via holes in thesubstrate.
 3. The manufacturing method as claimed in claim 1, whereinthe forming the interconnections and the connecting terminal-formingwirings includes: forming the connecting terminal-forming wiring as aninner layer of the substrate; forming two interconnections in parallelon the surface of the substrate; forming another interconnection thatconnects the two interconnections on the surface of the substrate; andforming a via hole conductor to be provided on the anotherinterconnection that connects the two interconnections and commonlyconnects the two interconnections and the connecting terminal-formingwirings; and wherein the forming the process openings includes removing,wholly or partially, the another interconnection that connects the twointerconnections and the via hole conductor.
 4. The manufacturing methodas claimed in claim 1, wherein the forming the interconnections and theconnecting terminal-forming wirings includes: forming theinterconnections on a surface of the substrate; and forming theconnecting terminal-forming wirings to be connected to theinterconnections on the surface of the substrate; and wherein theforming the process openings cuts off the connecting terminal-formingwirings by forming openings in the substrate.
 5. A method ofmanufacturing a card edge connector type printed circuit board,comprising: forming interconnections on a surface of a substrate byelectrolytic plating; forming connecting terminals by electrolyticplating at an edge of the surface of the substrate; connecting theinterconnections to the connecting terminals on the surface of thesubstrate by electrolytic plating; forming connecting terminal-formingwirings at an inner layer of the substrate; connecting theinterconnections to the connecting terminal wirings within thesubstrate; and forming process openings in the substrate substantiallyproximate to the interconnections to electrically isolate theinterconnections from the connecting terminal-forming wirings; andisolating the process openings from a conductive layer formed as anotherinner layer of the substrate.
 6. A card edge connector type printedcircuit board, comprising: forming interconnections on a surface of asubstrate by electrolytic plating; forming connecting terminals byelectrolytic plating at an edge of the surface of the substrate;connecting the interconnections to the connecting terminals on thesurface of the substrate by electrolytic plating; forming connectingterminal-forming wirings at an inner layer of the substrate; connectingthe interconnections to the connecting terminal wirings within thesubstrate; and forming process openings for electrically isolating theinterconnections from the connecting terminal-forming wirings; andelectrically isolating the process openings from a conductive layerformed as another inner layer of the substrate.